1. Field of the Invention
This invention relates to an improvement of an apparatus such as a camera or the like adapted to use a solar battery.
2. Description of the Related Art
An arrangement for causing the body of an apparatus having a panel to which a solar battery is attached and a secondary battery which is disposed within the body to be cooled by forming an air layer between the apparatus body and the panel, has been disclosed in U.S. patent application Ser. No. 08/257,117. An electronic apparatus developed as an improvement of this arrangement has been proposed in U.S. patent application Ser. No. 08/362,992. The improved electronic apparatus is designed to be capable of protecting the secondary battery and other parts vulnerable to heat even under such conditions that tend to cause the solar battery to have a high temperature. The electronic apparatus, which is a camera in this case, is arranged as described below with reference to FIGS. 16(a) to 16(c) through FIG. 20.
FIGS. 16(a) to 16(c) are views showing the camera as viewed from its bottom side which is opposite the side on which the shutter release button is located. FIG. 16(a) shows the camera in a portable, closed state. FIG. 16(b) shows the camera in a standby state with lens barrel 1b extended from a retracted state is as shown in FIG. 16(a). FIG. 16(c) shows the camera in a state having front cover 2 popped up for avoiding heat damage when generating electrical energy by placing the camera in direct sunlight so as to apply intense light to solar battery cells 2a. The state shown in FIG. 16(c) hereinafter will be called a pop-up state. FIG. 17 is an oblique view showing the camera as viewed from the side on which the shutter release button is provided. FIGS. 18 and 19 are views showing the internal structure of the safety arrangement which brings about the pop-up state as shown in FIG. 16(c).
Referring to these figures, the camera body 1 includes photo-taking lens barrel 1b which is adapted to be extended from a retracted position to a photo-taking position in the standby state as shown in FIG. 16(b), a stopper part 1c which will be described later and an aperture part (for a film cassette) which is not shown but is located in a lower part as viewed from these figures. A lithium-ion secondary battery 1a is installed in a built-in fashion within the camera body in a position as indicated by the broken line in FIG. 17.
The front cover 2 is arranged to be rotatable on a rotation shaft 2c which is fitted in holes (not shown) provided in the camera body 1. A torsion spring 4 which is shown in FIG. 19 is arranged to constantly urge the front cover 2 to swing counterclockwise. In the portable, closed state as shown in FIG. 16(a), however, the front cover 2 is kept in this state by the action of a first lock claw 6. Five amorphous semiconductor solar battery cells 2a are disposed on the outer surface of the front cover 2 as shown in FIG. 17. The solar battery cells 2a are series-connected as shown in FIG. 20. When the sunlight falls on the solar battery cells 2a, an electrical current is generated. Then, the lithium-ion secondary battery 1a is charged by flow of the electrical current through a reverse-blocking diode 21 (see FIG. 20). The front cover 2 is provided further with a cutout part 2b which is arranged to guide a slidable operation knob 3b, a shutter release button 2d, a pop-up button 2e for bringing about the pop-up state in response to an external operation thereon, a strap attaching part 2f and a strap 2g which is attached to the strap attaching part 2f. Further, as shown in FIGS. 18 and 19, a shaft 2h is arranged to slidably guide a main switch lever 3 on the inner side of the front cover 2 in a part hidden from the sight of the camera user.
The main switch lever 3 has slots 3a which are fitted on the shaft 2h and is thus carried by the shaft 2h to be slidable to the right or left as shown in FIG. 19. A spring 5, one end of which is hooked on an arm part 3c of the main switch lever 3, is arranged to constantly urge the main switch lever 3 to the left as viewed in FIG. 19. The main switch lever 3 is locked to its position shown in FIG. 19 by means of a stopper which is not shown. The main switch lever 3 is provided with an operation knob 3b which is provided for operation by the camera user, a tapered protruding part 3d which is arranged to push an unlocking part 6c of the first lock claw 6 provided for locking the front cover 2, and a lock part which is not shown but is arranged to keep the camera body 1 and the front cover 2 in a positional relation as shown in FIG. 16(b).
The first lock claw 6 has a hole 6a fitted on a shaft (not shown) provided within the camera body 1 and is thus swingably carried by that shaft. A spring 7 which has one end of it hooked on one end of an arm part 6d of the first lock claw 6 is arranged to constantly urge the first lock claw 6 to swing clockwise. A stopper which is not shown is arranged to keep the first lock claw 6 in its position shown in FIG. 19 when the camera is in the state shown in FIG. 16(b). A lock part 6b of the first lock claw 6 is arranged to be movable back and forth into and out of a slot 8b of a lock lever 8. In the portable, closed state as shown in FIGS. 16(a), etc., the lock part 6b has been moved forward to be fitted into the slot 8b of the lock lever 8 and to keep the front cover 2 in its closed position of FIG. 16(a) against the urging force of the torsion spring 4. When the unlocking part 6c of the first lock claw, which is located on the opposite side of the lock part 6b, is pushed by the tapered protruding part 3d of the main switch lever 3, the first lock claw 6 is caused to swing counterclockwise against the urging force of the spring 7. The swing motion retracts the lock part 6b away from the slot 8b to unlock the front cover 2. As a result, the portable, closed state of FIG. 16(a) changes into the standby state as shown in FIG. 16(b).
The lock lever 8 has a hole 8a in which a shaft (not shown) of the front cover 2 is fitted and is thus swingably carried by that shaft. The slot 8b of the lock lever 8 is arranged to allow the lock part 6b of the first lock claw 6 to be fitted therein as mentioned above. In the states shown in FIGS. 16(a), 16(b), and 19, a lock claw part 8c of the lock lever 8 is in mesh with a lock claw part 9b of a second lock claw 9. Therefore, the lock lever 8 is kept together with the front cover 2. In the pop-up state shown in FIG. 16(c), an L-shaped part of the lock claw part 8c of the lock lever 8 is abutting on a stopper part 1c of the camera body 1. The camera is thus arranged such that, even if the front cover 2 is pulled up inadvertently by the user in this state, the pulling force is not directly exerted on the first lock claw 6.
The second lock claw 9 is swingably supported by a shaft (not shown) of the front cover 2 with the shaft fitted in a hole 9a of the second lock claw 9. A spring 10 which is hooked on one end of an arm part 9d of the second lock claw 9 is arranged to constantly urge the second lock claw 9 to swing counterclockwise. The second lock claw 9 is, however, kept in the state shown in FIG. 18 by a stopper which is not shown. With the second lock claw 9 provided with the lock claw part 9b as mentioned above, in the portable state as shown in FIGS. 19, etc., the lock claw part 8c of the lock lever 8 is in mesh with the lock claw part 9b to prevent the counterclockwise swing. The second lock claw 9 is further provided with a hooking part 9c which is arranged on the side opposite to the lock claw part 9b and has a wire 11 made of a shape memory alloy of nickel and titanium hooked thereon.
The wire 11 which is made of the shape memory alloy is carried by a shaft arranged in a known eccentric manner. The wire 11 is extended along the reverse surface of the front cover 2 through an adjusting pulley 12, with its tension adjusted during the manufacturing process, and is connected to a shaft of the front cover 2 at one end 11a by a known manner (see FIGS. 18 and 19). When intense sunlight is applied to the surfaces of the solar battery cells 2a on the front cover 2 and, if the temperature of the front cover 2 exceeds, say, 65.degree. C., the shape memory alloy wire 11 transforms and shrinks to cause the second lock claw 9 to swing clockwise against the urging force of the spring 10 and thus to disengage the lock claw part 9b from the lock claw part 8c of the lock lever 8.
Further, the camera is arranged such that the lock claw part 8c of the lock lever 8 can be manually unlocked from the lock claw part 9b of the second lock claw 9 by the user by pushing a pop-up button 2e shown in FIG. 17. In this case, the pushing force on the pop-up button 2e acts to swing the second lock claw 9 clockwise.
FIG. 20 shows the power supply circuitry of the camera arranged as described above. Referring to FIG. 20, the solar battery cells 2a are arranged on the front cover 2. The lithium-ion secondary battery 1a is disposed within the camera body 1. A diode 21 is arranged to block the flow of reverse current. An overcharge preventing circuit 22 is arranged in a known manner. A microcomputer 23 is arranged to control the various circuits disposed within the camera body 1. A main switch 24 is arranged to turn on when the front cover 2 is opened.
The camera arranged as described above can be carried by the user in the state shown in FIGS. 16(a), etc., with the strap 2g (FIG. 17) placed on the shoulder of the user. Even while the camera is in such a state, the lithium-ion secondary battery 1a can be charged by light falling on the solar battery cells 2a.
In taking a picture, when the user slides the operation knob 3b of the main thumb switch lever 3 to the right as viewed on FIG. 16(a), the front cover 2 is caused to swing counterclockwise by the urging force of the torsion spring 4. More specifically, with the knob 3b slid to the right from its position shown in FIG. 19, the tapered protruding part 3d pushes the unlocking part 6c of the first lock claw 6 to cause the first lock claw 6 to swing counterclockwise as viewed in the drawing against the urging force of the spring 7. The lock part 6b of the first lock claw 6 then retreats from the slot 8b of the lock lever 8 which is held integrally with the front cover 2. As a result, the front cover 2 is released from a state of being locked to the camera body 1. The front cover 2 is thus allowed to swing counterclockwise by the urging force of the torsion spring 4. (In actuality, the camera body 1 is caused to reactively swing in the opposite direction with the front cover 2 held by the hand.)
When the front cover 2 swings to its position shown in FIG. 16(b), the camera body 1 and the front cover 2 are kept in this positional relation by means of a lock member which is not shown, as mentioned above. The main switch 24 (shown in FIG. 20) then turns on. The lens barrel 1b is drawn out and the camera assumes the standby (photo-taking) state. Then, a picture can be taken, in the same manner as with an ordinary camera, by deciding the composition of the picture by viewing through a viewfinder which is not shown and by pushing the shutter release button 2d.
In bringing the camera from the standby state back to the portable, closed state, the camera is operated as follows. The operation knob 3b of the main switch lever 3 is slid upward, as viewed in FIG. 16(b). The upward sliding motion of the operation knob 3b releases the front cover 2 from the state of being locked to the camera body 1 by the lock part which is not shown. With the front cover 2 thus unlocked, the camera body 1 is caused to swing counterclockwise against the urging force of the torsion spring 4. The lock part 6b of the first lock claw 6 then abuts on the lower face of the lock lever 8 and overrides the latter, as the upper part of the lock part 6b is tapered as shown in FIG. 16(b) while the lower face is chamfered to smooth the overriding motion. As a result, the first lock claw 6 engages the lock lever 8 to bring the camera back to the portable, closed state. In the portable state, the main switch 24 is in an off-state to prevent the camera from responding to any inadvertent pushing operation on the shutter release button 2d.
In a case where the user wishes to charge the battery of the camera under direct sunlight, the pop-up button 2e is pushed by the user in the portable, closed state shown in FIGS. 16(a), etc. The second lock claw 9 is then caused to swing clockwise against the urging force of the spring 10. The lock claw part 9b of the second lock claw 9 then disengages from the lock claw part 8c of the lock lever 8. The front cover 2 is allowed to be swung counterclockwise by the urging force of the torsion spring 4 which is hooked between the front cover 2 and the camera body 1. At this time, the lock part 6b of the first lock claw 6 is still engaging the slot 8b of the lock lever 8. Therefore, the lock lever 8 swings on the hole 8a along with the counterclockwise swinging motion of the front cover 2.
The lock lever 8 and the front cover 2 stop swinging with the lock part 8c of the lock lever 8 coming to abut on the stopper part 1c of the camera body 1. The camera is thus brought into the pop-up state in which the front cover 2 is half open as shown in FIGS. 18 and 16(c). If the camera is left in this state, for example, in a parked automobile in a midsummer outdoor environment, the temperature of the solar battery cells 2a of the front cover 2 rises close to 90.degree. C. However, with the camera in the pop-up state, a thick layer of air A is provided between the camera body 1 and the front cover 2 to prevent the temperature of the camera body 1 from rising to a temperature exceeding 60.degree. C., as when the camera body 1 is under a parasol.
Therefore, the lithium-ion secondary battery 1a which is disposed in the lower part of the camera body and a film have a temperature not exceeding 50.degree. C., which is about the same as the temperature of air inside the automobile. The secondary battery 1a and the film thus would never be substantially damaged even if the camera is left under such a condition over a long period of time.
In a case where the camera is inadvertently left, for example, on the dashboard of an automobile in its portable, closed state and is exposed to high temperature air and high illuminance direct sunlight, a safety arrangement of the camera shows an advantageous effect. Before describing this effect, the state of the camera obtained without the safety arrangement under such conditions is first described.
According to tests conducted by the inventors of the present invention, the temperature obtained inside of an automobile when it is parked under a clear sky in an equatorial area, such as Malaysia, reaches 90.degree. C. or thereabout on the surface of a dashboard and about 85.degree. C. at parts of seats exposed to direct sunlight. Then, the average temperature of convective air inside of the automobile is about 52.degree. C. This condition reaches an equilibrium state in one or two hours after the commencement of exposure to the direct sunlight.
With the camera placed in the above-stated environment, the temperature of the solar battery cells 2a of the front cover 2 exceeds 90.degree. C. in about one hour. The temperature of a thin air layer between the front cover 2 and the camera body 1 and the temperature of the front surface of the camera body 1 also become very high reaching 85.degree. C. or so. (Since the air layer cannot be allowed to be more than several mm in thickness in respect of portability, the speed of convection taking place between the outside air and the air layer is only about several mm/sec due to a viscous resistance between the reverse surface of the front cover 2 and the front surface of the camera body 1. Hence, the air layer hardly has any cooling effect on the reverse surface of the front cover 2.) The heat not only damages parts inside of the camera but also causes the temperature of the lithium-ion secondary battery 1a to exceed 65.degree. C. and that of the film to exceed 60.degree. C., thereby also damaging the secondary battery and the film.
The exposure of the camera in the state shown in FIG. 19 to the above-stated severe ambient condition causes the temperature of the front cover 2 to exceed 65.degree. C. in 20 min or so. Then, the shape memory alloy wire 11 shrinks to cause the second lock claw 9 to swing clockwise. Therefore, as in the case where the pop-up button 2e is pushed, the lock claw part 9b of the second lock claw 9 disengages the lock claw part 8c of the lock lever 8. Then, as mentioned above, the front cover 2 is caused to swing counterclockwise (pop up) by the urging force of the torsion spring 4, following the counterclockwise swing of the lock lever 8 on its hole 8a. As a result, the camera is brought into the pop-up state as shown in FIGS. 16(c) and 18.
With the camera in this state, the air layer between the front cover 2 and the camera body 1 expands from a thickness of tens to scores of mm. Therefore, the expanded air layer permits convective communication with the external air (the maximum temperature of the air is 52.degree. C.). The front cover 2 and the front surface of the camera body 1 are thus cooled down. Particularly, the front surface of the camera body 1 is cooled to about the same temperature as the air temperature inside of the automobile, because it is located under the shadow of the front cover 2. Although the temperature of the front cover 2 may become still higher by absorbing the energy of the sunlight, it never exceeds 90.degree. C. as the reverse surface thereof is cooled by the external air.
The secondary battery and the film which are disposed within the camera body are thus effectively prevented from being damaged even under such a condition that increases the temperature of the solar battery part. Most of the compact cameras are provided these days with protection covers, or barriers, for covering their lenses when they are not used and also with built-in flash devices for shooting under low lumunance conditions. The cameras of this kind, therefore, must be provided with many built-in component parts for performing the above-stated functions. This requirement inevitably results in some increase in size and cost of the compact cameras and also some restriction on their designs.
In this respect, cameras disclosed in U.S. Pat. No. 4,557,571 and U.S. Pat. No. 4,319,818 are arranged to mitigate this shortcoming by having a flash device built in a barrier forming part of the camera and to have the barrier act as a flash device during picture taking, so that a relatively greater number of parts are arranged to perform the combined functions than with other compact cameras.
In the case of another camera disclosed in U.S. Pat. No. 4,897,680, a reflection mirror for performing a light condensing action in a flash device is arranged to open above the camera as necessary.
Among the apparatuses of the prior art cited above, however, the electronic apparatus, i.e., the camera of U.S. patent application Ser. No. 08/362,992 has presented the following problems.
i) The protective case, i.e., the front cover 2, of the camera is arranged to be opened and closed by a manual operation. It is, therefore, difficult to modify this camera into an automatic standby type camera which is arranged to be automatically brought into an operative photo-taking (shooting) state and also to be brought back to a non-operative shooting state. Further, the barrier closing operation necessitates closing the barrier while charging the torsion spring which is arranged to urge the barrier in the direction of opening. Therefore, the camera has poor operability. PA1 ii) An increase in temperature automatically brings the protective barrier to its pop-up position. However, the camera is not designed to automatically bring the barrier back to its original position when the temperature drops. PA1 iii) To solve the problem of the paragraph i) above, if another actuator is arranged to automatically open and close the protective barrier in addition to the actuator used for popping up, it causes an increase in cost.
In the cases of the cameras disclosed in U.S. Pat. No. 4,319,818 and U.S. Pat. No. 4,557,571 and cited above as examples of the prior art, the possibility of having a red-eye phenomenon while taking a portrait is mitigated by arranging the flash device away from the photo-taking optical axis. However, the arrangement of having the light source disposed on the side of the barrier complicates an electrical connection part between the light source and the camera body and thus causes an increase in cost. Further, the arrangement inevitably results in a shorter distance between the light source and a part (such as a Fresnel lens) condensing the light of the light source. The shorter distance thwarts an efficient condensing action.
In another camera disclosed in U.S. Pat. No. 4,897,680, a flash device which is arranged to have only its reflector popped up does not present the above-stated problems of the U.S. patent application cited above. The camera, however, must be provided with protection covers discretely arranged for the photo-taking lens and a viewfinder part. That arrangement thus causes an increase in cost and imposes some restrictions on the design of the camera.